from 350 to 470, there's a 120 difference.
now, if we take 350 to be the 100%, what is 120 off of it in percentage?
[tex]\bf \begin{array}{ccll}
amount&\%\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
350&100\\
120&p
\end{array}\implies \cfrac{350}{120}=\cfrac{100}{p}
\\\\\\
p=\cfrac{120\cdot 100}{350}\implies p\approx 34.29[/tex]